In current Radar tracking systems monopulse is used as the primary tracking technique. Conventional phase monopulse tracking (phase monopulse) utilizes a single antenna with four phase centers or a set of four separate antennas. The output of the four phase centers (1, 2, 3, and 4) (see FIG. 1) are fed into an RF circuit to form three channels of information (Sum, Yaw Delta, and Pitch Delta). The Sum channel is formed from 1+2+3+4. The Yaw Delta is formed from (1+3)-(2+4). The Pitch Delta is formed from (1+2)-(3+4). The sum channel is sent through a 90.degree. phase shifter, then all three channels are sent through an AGC with the sum channel used as the normalizing signal. Then the normalized sum is correlated with each of the deltas to form epsilon pitch and epsilon yaw.
The major problem associated with this method is the matching of the three channels. This is done at the time of building of the system with no calibration possible after the system is assembled. The monopulse network used to form the sum and deltas is an added complexity to the system. It also introduces errors and is an added weight to the system.